1. Field of the Invention
The subject invention relates to an absorber for a fluid delivery system, and more particularly, to a multi-layered gas-filled bladder for accommodating changes in the fluid characteristics that exist within a fluid delivery system, including, for example, absorbing volume expansion due to water heating within the fluid delivery system, suppressing or arresting pressure surges associated with a shock wave or water hammer propagating through the water delivery system, or accommodating volume expansion within a reverse osmosis water filtration system to provide a storage volume of fluid.
2. Description of the Related Art
Incompressible fluids (such as water) produce volumetric affects under certain conditions. For instance, when heated, water expands in volume. Within a fixed contained system, this heated expansion of water will increase the pressure within the system. Another volume affect is that shock waves occur in fluid systems when a flow in the supply is quickly and abruptly closed or when a force in flow is suddenly changed. The fluid system is usually a liquid system, but sometimes also is a gas system. Such shock waves commonly occur when a valve is closed at an end of a piping system, resulting in a pressure wave propagating in the pipe, which is commonly referred to as a water hammer.
The change in pressure within a fluid delivery system, by thermal expansion or by closure of the supply or sudden change in momentum of the flow can cause substantial problems. For example, a buildup of water flow can be created, resulting in a pressure spike that can physically rattle the pipes, causing noise and vibration. This noise and vibration can often be heard and felt within a dwelling or building. The water hammer also produces stress on the pipes and components in the piping system, which can lead to failure in the system and water damage.
While the presence of the water hammer phenomena cannot always be anticipated when planning plumbing layouts, it can be corrected. In particular, in order to prevent violent pipe noise, system failure and damage, devices have been developed to provide an alternate path for dissipating or otherwise absorbing high pressure spikes in a fluid delivery system.
For example, shock suppressors have been developed to reduce the pressure spike in a fluid delivery system. Such shock suppressors, also referred to as water hammer arrestors, utilize a pre-charge of air to provide an air cell or air cushion that absorbs the pressure shock in the system. One example of such a device includes an air chamber in the form of a vertical pipe located in a wall of piping at a point located near a faucet or valve.
The air chamber acts as a cushion to prevent impact between the water and the piping. As the pressure shock enters the shock suppressor, the air cushion compresses, the air pressure increases and the shock is absorbed. These shock suppressors can be incorporated into a system component such as a valve or the like, and generally include a movable piston that is sealed to the inner diameter of the pipe. The air charge on one side of the piston provides resistance to water pressure on the other side of the piston until the water pressure increases above the air charge pressure. When this occurs, the expanded water pushes the piston and enters the pipe.
Shock absorbers have also been developed which include a flexible diaphragm separating the air cushion from the water stream that enters the shock absorber. It can be positioned at an appropriate location within a piping system so that when water flow is abruptly stopped or changed within the system, the water can enter the shock absorber. As the water enters the shock absorber, it comes into contact with the diaphragm which is pushed towards the air cushion on a side opposite the water side, compressing the air cushion. The contact with the diaphragm and compression of the air cushion acts to absorb the pressure shock.
While such shock suppressors are capable of reducing water hammer and addressing the problems resulting therefrom, they are susceptible to losing their ability to absorb pressure shock and volume expansion over time. In particular, the diaphragm often weakens and fails, for example, at an outer edge or at an inside portion along the diaphragm. This failure reduces and often eliminates the ability of the shock suppressor to absorb water and pressure shock.
Furthermore, if the diaphragm fails and allows water to pass into the air cushion side, the water will come into contact with what is generally an unprotected metal housing, leading to corrosion and rust in the system. Consequently, regular maintenance of this type of shock absorber is required, often resulting in the need to replace the entire system. In addition, in this type of shock suppressors, a pre-charge of air is required to provide the air cushion. This complicates the design and application and maintenance of the shock absorber.
The present invention also provides an improved volume expansion absorber that absorbs a volume of water from a system. For example, when water in a system is heated, it expands, which results in an increased volume of water in the system that must be accommodated. The absorber readily accommodates this increased volume of water. The present invention also provides an absorber that accommodates volumetric expansion within a reverse osmosis water filtration system to provide a storage volume of fluid for subsequent delivery to a faucet or tap for consumption.